Using anisotropic holographic metasurfaces to transform the creeping waves into circularly polarized (CP) beams has initiated the quest for tangible applications in different disciplines. However, the present designs are only limited to the planar impedance surfaces with rare studies concerning the linear-to-circular polarization converting holographic metasurface over the conformal platforms. In this paper, we demonstrate the perfect transformation of linearly polarized (LP) surface waves into CP waves through cylindrical anisotropic holographic metasurfaces consisting of gradient H-shaped slits etched on the periodic circular patches. Especially, the linear-to-circular polarization conversion rate can always maintain a very high level for the beam synthesis no matter how the curvature of the metasurface changes, and such high-purity CP beams also demonstrate very good quality of steerable characteristics over conformal surfaces. Our approach, using anisotropic holographic metasurfaces to transform the creeping waves into high-purity CP beams, should pave the way for more advanced functional meta-device designs over the non-planar impedance surfaces.

We introduce a partially reflecting metasurface sandwich (PRMS) into the Fabry-Pérot (FP) resonator antenna for generating split circularly polarized (CP) beams with opposite helicities for Ku-band applications. The PRMS consists of top gradient metasurfaces and bottom periodic metasurfaces connected by the metallic cylinders through central holes in the intermediate defected metal partition. Through integrating such a PRMS, the proposed FP resonator antenna would be capable of transforming the linearly polarized waves from the feed into well-collimated split left-hand CP (LHCP) and right-hand CP (RHCP) waves with highly efficient linear-to-circular polarization conversion simultaneously. Our design should offer an efficient way to build up more advanced FP resonator antennas with specific radiating characteristics using functional metasurfaces.

We propose the metasurface-based cavities for splitting a linearly polarized (LP) electromagnetic wave into two symmetric circularly polarized (CP) beams with opposite helicities. More specifically, periodic strip slits and rectangular C-slits etched on substrate integrated waveguide cavities are shown to be capable of perfectly coupling the LP wave into the cavities from the strip slit array, and then releasing them with specific polarization directions according to the orientations of the C-slits. Such metasurface-based cavities with gradient oriented C-slit array would further create the opposite equivalent phase gradients for the right-hand and left-hand CP transmitting waves that are decomposed from the released LP wave with anomalous birefractions and polarization conversion simultaneously.

We demonstrate the frequency scanning performances from a linearly tapered rectangular waveguide slot array antenna using the spatial angular filtering meta-surface. To be more specifics, the meta-surface at the narrow side of the waveguide is shown to be capable of releasing different wavelength energies when under the illuminations from different incident angles, while the tapered waveguide is proposed to mimic the oblique incidence and thus functions as the excitation of the antenna. Such frequency scanning radiations can also be extended for both orthogonally polarized electromagnetic fields when integrated with another polarization selective surface properly behind the meta-surface. Finally, we carry out the experiments to verify our proposed designs and demonstrate the excellent beam scanning performances when the frequency is changing.

We introduce a meta-surface cavity into the waveguide slot array design and demonstrate the perfect generation of dual-circularly polarized (CP) dual-beams, where the cavity consists of meta-surface coated dielectric substrate surrounded by metallic vias and metal walls. When integrated with the rectangular waveguide, the meta-surface cavity functions as the leaky wave passage, capable of coupling the linearly polarized incidence from the feed into the cavity and releasing the resonant mode with birefringent radiations of right-hand and left-hand CP waves. Our design, performing the beam splitting and polarization conversion simultaneously as a waveguide slot array, should pave the way for building up more advanced meta-surface-based architectures for the manipulations of electromagnetic fields in the transmission regime.

We demonstrate the enhanced polarization modulation of electromagnetic fields through hybrid skew-ring-resonator-graphene meta-surfaces that can dynamically transform the linearly polarized waves into its cross-linearly polarized counterparts or the circularly polarized waves. Such a meta-surface consists of a grounded skew-ring resonator array inserted with a monolayer graphene sheet that controls the electromagnetic interactions between the skew-ring resonators and the ground. Especially, the reconfigurable characteristic of graphene enables the reflections to be capable of converting from the cross-linearly polarized fields to the circularly polarized waves by setting different Fermi energies with the same original co-linearly polarized incidence. Finally, we demonstrate that the bandwidth of the cross-polarization conversion would be greatly expanded when the monolayer graphene sheet is integrated with skew-bar-resonator meta-surfaces.